#include<iostream>
using namespace std;
class A {
public:
	void func() {
		cout << "A::func" << endl;
	}
	virtual void gun() = 0 {
		cout << "A::gun" << endl;
	}
	virtual ~A() = default;
};

class B :public A {
public:
	void func(int b) {
		cout << "B::func" << endl;
	}
	virtual void gun() {
		cout << "B::gun" << endl;
	}
};

int main() {
	B b;
	b.A::gun();
}